This is what the verse said: “Lest you delineate a path of life: Her tracks wander; you will not know” (Proverbs 5:6) – what is meant by “lest you delineate [tefales] a path of life”? Rabbi Abba bar Kahana said: The Holy One blessed be He said: ‘Do not sit and evaluate the mitzvot of the Torah, as it is stated: “He weighed mountains with a scale [peles]” (Isaiah 40:12). Do not say: Since this mitzva is great, I will perform it, as its reward is substantial, but since that one is a minor mitzva, I will not perform it.’
What did the Holy One blessed be He do? He did not reveal to people what is the reward granted for each and every mitzva, so that they would perform all the mitzvot without guile. From where is this derived? “Her tracks wander; you will not know.”
To what is the matter comparable? To a king who hired laborers and took them into his orchard [containing various trees]. He was unspecific, and did not reveal to them the wages for the [different trees of the] orchard, so they should not forsake [working on] those with minimal wages and go and work [only] on those with substantial wages. In the evening, he summoned each one of them and said to him: ‘Beneath which tree did you work?’
He said to him: ‘Beneath this one.’ He said to him: ‘That is a pepper tree, its wages are one gold piece.’ He summoned another and said to him: ‘Beneath which tree did you work?’ He said to him: ‘Beneath this one.’
He said to him: ‘Its wages are one-half gold piece, as it is a [tree with] white blossoms.’6And not very valuable. He summoned another and said to him: ‘Beneath which tree did you work?’ He said to him: ‘Beneath this one.’ He said to him: ‘That is an olive tree, its wages are two hundred zuz.’
They said to him: ‘Should you not have informed us [at the outset] which tree has abundant wages so that we could work beneath it?’ The king said to them: ‘Had I informed you, how would all of my orchard have been cultivated?’ So, too, the Holy One blessed be He did not reveal the reward granted for each of the mitzvot, with the exception of two mitzvot – the one of the greatest difficulty, and the one of the least difficulty.
Honoring one’s father and mother is of the greatest difficulty, and the reward granted for it is prolonging of one’s days, as it is stated: “Honor your father and your mother, so that your days will be prolonged” (Exodus 20:12). The one of least difficulty is the dispatching of the mother bird, and what is its reward? Prolonging of days, as it is stated: “You shall surely send away the mother…and prolong your days” (Deuteronomy 22:7).7This teaches that the amount of reward for a mitzva is not necessarily commensurate with its level of difficulty. That is, “if a bird's nest will happen before you.”